Elucidation of the mechanisms which control the proliferation and differentiation of human cells is essential to our understanding of the pathogenesis and progression of a number of diseases including cancer. Our studies have focused on the ErbB family of receptors and ligands, which play an important role in the proliferation and differentiation of human cells. These studies have provided insights into the control of cell division and have progressed our understanding of growth factor-mediated signal tranduction, in general. A major therapeutic use which has been proposed for recombinant growth factors is in wound healing indications. A number of growth factor-based therapies for wound healing indications are currently under review in CBER. Research which is directed towards elucidation of the structure and mechanism of action of growth factors is essential to our ability to effectively review these applications. In particular, CBER reviews a number of INDs which involve ligands which signal through the ErbB family of receptors and thus, our research is directly related to our regulatory responsibilites. A thorough understanding of the nature of growth factor-induced cell growth is important in evaluating the safety and efficacy of these proposed products for wound healing and for cancer indications.